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CO2 cooling?

by Andre
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Andre
#1
Aug26-08, 10:06 AM
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http://www.informaworld.com/smpp/con...8582859~db=all



G. V. CHILINGAR, L. F. KHILYUK, and O. G. SOROKHTIN, 2008, Cooling of Atmosphere Due to CO2 Emission, Energy Sources, Part A, 30:1–9, 2008 ISSN: 1556-7036 print/1556-7230 online DOI: 10.1080/15567030701568727

Heads and tails of the study:
Introduction

Traditional anthropogenic theory of currently observed global warming states that release of carbon dioxide into atmosphere (partially as a result of utilization of fossil fuels) leads to an increase in atmospheric temperature because the molecules of CO2 (and other greenhouse gases) absorb the infrared radiation from the Earth’s surface. This statement is based on the Arrhenius hypothesis, which was never verified (Arrhenius, 1896).
The proponents of this theory take into consideration only one component of heat transfer in atmosphere, i.e., radiation. Yet, in the dense Earth’s troposphere with the pressure pa > 0:2 atm, the heat from the Earth’s surface is mostly transferred by convection (Sorokhtin, 2001a). According to our estimates, convection accounts for 67%, water vapor condensation in troposphere accounts for 25%, and radiation accounts for about 8% of the total heat transfer from the Earth’s surface to troposphere.

Thus, convection is the dominant process of heat transfer in troposphere, and all the theories of Earth’s atmospheric heating (or cooling) first of all must consider this process of heat (energy)– mass redistribution in atmosphere (Sorokhtin, 2001a, 2001b; Khilyuk and Chilingar, 2003, 2004). …

...

Conclusions

…Accumulation of large amounts of carbon dioxide in the atmosphere leads to the cooling, and not to warming of climate, as the proponents of traditional anthropogenic global warming theory believe (Aeschbach-Hertig, 2006). This conclusion has a simple physical explanation: when the infrared radiation is absorbed by the molecules of greenhouse gases, its energy is transformed into thermal expansion of air, which causes convective fluxes of air masses restoring the adiabatic distribution of temperature in the troposphere. Our estimates show that release of small amounts of carbon dioxide (several hundreds ppm), which are typical for the scope of anthropogenic emission, does not influence the global temperature of Earth’s atmosphere.
I can follow that logic. Discussion?
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Count Iblis
#2
Aug26-08, 05:05 PM
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I don't follow the logic at all. You need warming due to absorption of infrared radiation leading to expansion and more convection and then you get a net cooling? But if you get a net cooling you don't have the warming you need to explain the expansion and the extra convection you need. It is self contradictory.
ray b
#3
Aug27-08, 02:43 AM
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are not the upper levels of the atmosphere near the tropopause cooler then expected
where you get the .2 atm
while the lower air near surface air is warmer

so hot or cooler may depend on how high up you are

Andre
#4
Aug27-08, 08:58 AM
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CO2 cooling?

Quote Quote by Count Iblis View Post
I don't follow the logic at all. You need warming due to absorption of infrared radiation leading to expansion and more convection and then you get a net cooling? But if you get a net cooling you don't have the warming you need to explain the expansion and the extra convection you need. It is self contradictory.
Okay, Indeed, it's not happening on the same levels. Let me elaborate.

First some understanding about convection:

http://www.ace.mmu.ac.uk/eae/Weather...onvection.html

One way that heat is transferred through air is by convection. Convection of heat energy in the atmosphere involves the movement of air. Air is a poor conductor of energy, so convection is a major process of energy movement in the Earth’s atmosphere. In the atmosphere, convection occurs when a shallow layer of air in contact with a hot surface warms by conduction, acquires buoyancy (warmer air is less dense than colder air), and rises, taking with it the energy that it stores. As the Earth is heated by the Sun, bubbles of hot air called thermals rise upward from the warm surface....con'td
Note that convection is visible most of the time as it produces cumulus clouds, thunderstorms, tornadoes, hurricanes.

Hence, convection is a means of transporting and distributing heat-energy within the atmosphere, causing the higher levels to be warmer than the natural lapse rate from the black body temperature. Why? because convection due to solar heat only works at day time, not at night, when the Earth cools due to radiation. This only makes the air in contact with the surface cooler and hence more dense, which prevents convection backwards.

However, the warmer air that has convected to higher atmospheric layers also radiates out heat, basically 50% to the Earth and 50% to the universe, also cooling in the process, not only at daytime but also at night!

Now the article argues that more greenhouse gas enhances the transfer of heat energy from the surface to the lower layers of the atmosphere, which obviously gets warmer faster but this amplifies the rate of convection and also the rate of cooler air from aloft replacing the convecting air, neutralizing the warming effect at the surface.

At the higher altitudes however, the increase of concentration of greenhouse gasses makes the energy radiation out of the atmosphere more effective, which increases the cooling rate, which is supposed to balance the increase of energy at the surface.

What they don't even consider, is that the overal effect of the 24/7 day night operation of enhanced radiative cooling in the upper atmosphere should compensate more than for the daytime only increase of thermal energy convection. Hence increase of greenhouse gasses seems to cause a net stronger radiative cooling.

Does that help?

Notice again that the greenhouse effect hypotheses attributes the difference between blackbody temperature and actual temperature attributes to radiation, whereas in reality this difference is mainly caused due to the one way convection of energy, only up, not down, just like a vertical conveyor belt..
blimkie.k
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Aug27-08, 09:04 AM
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I could see inscreased co2 in the atmosphere eventually having a cooling effect. According to global warming increased co2 in the atmosphere inscreases the greenhouse effect and increases temperature. If it is true that temperature is increasing will that not increase evaporation resulting in heavier cloud cover and rain. Also melting of ice caps should cool the ocean or slow down the currents which carry heat away from the equator. I suppose this could also have a negative impace on regions near the equator.

Anyways I live in south east ontario and this summer was not very summerish at all. It was not as hot as it should have been and it rained a hell of alot. We broke 100 year old rainfall records in some areas. There was hardly any days with clear blue skys. Even the nicest days were still filled with cumulus clouds. Shady or even rainy periods. I have been wondering if its just a freak summer or if it could have something to do with climate change.
Also the farmers almanac calls for a colder then normal winter. Just awesome.
vanesch
#6
Aug27-08, 09:12 AM
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I think qualitative dynamics like this doesn't mean much, especially when different dynamics work in opposite directions: one should put them in a computational model and see how all this behaves. In fact, as long as one doesn't have a computational model that is 1) based upon sound physical basis (and not on empirical parameter fitting black box dynamics) and 2) corresponds to genuine experimental data, I think speculation is running loose.
Andre
#7
Aug27-08, 09:24 AM
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But it's a start, since classic greenhouse effect ideas might underestimate the energy transport by convection, it's unlikely that the current models do justice to the effect of convection.
wolram
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Aug27-08, 12:19 PM
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This may be totally naive, but why can not scientists fill a chamber with gasses in some proportions and measure it properties to reflect, absorb whatever light/heat.
Gokul43201
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Aug27-08, 03:16 PM
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Quote Quote by wolram View Post
This may be totally naive, but why can not scientists fill a chamber with gasses in some proportions and measure it properties to reflect, absorb whatever light/heat.
Because the physics is not scale invariant. Nor is there any kind of easy scaling theory for any of this.
Andre
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Aug27-08, 03:42 PM
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Indeed, there isn't, moreover the processes are not linear. You could compare the double effect of heating and cooling with a tap opening a bit more (heating) to fill a bucket with a hole in the bottom, which we make a bit bigger (cooling). there is no way to tell what the water level is going to do, without quantification.

Although you could quantify both warming and cooling rates logaritmically proportional to the density of the greenhouse gas, but quantifying the increase in convection rate would be rather complicated especially when the role of water evaporation and condensation is taken into consideration.

It may be noted that problems in the basic mechanisms of the greenhouse idea have been signalled by Miskolsci here as well as Douglass et al here.

Bottom line however from the study remains that it makes a case that the atmosphere is primarily heated by convection instead of radiative effects. It appears that this would reduce the effect of radiative forcing heating or greenhouse effect considerably.
Andre
#11
Aug28-08, 05:55 AM
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It may be recalled that also our cbacba had some issues with his model here.

Quote Quote by cbacba
That brings to question, what does cause the earth to be warmer if ghgs don't have much of anything to do with it.
It seems that Chilingar et al 2008 pretty much have answered that question, convection. Curiously enough I learned that already some four decades ago, going for my glider flying permit. However, there is very little mentioning of convection in the IPCC 4AR WG1 climate issues. Why?
billiards
#12
Aug28-08, 01:28 PM
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But surely if CO2 becomes more important to heating at higher altitudes, then this would make the atmosphere more buoyantly stable. In other words, wouldn't increasing CO2 have the opposite effect to that proposed, ie, it would tend to inhibit convection??
Andre
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Aug28-08, 01:41 PM
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The idea is, that it becomes more important at cooling the higher altitudes by radiating out the convected energy.

Alternately consider the null hypothesis, suppose that there was no greenhouse gas in the atmosphere. It would still be heated by conduction at the lowermost levels, which would still generate convection.

But since the convection is one way traffic only, without the possibility to loose that heat energy by radiation, the atmosphere would continue to heat up by convection until the lapse rate was to become stable, preventing further convection, then the atmosphere would be a lot warmer than without the radiative cooling at higher levels.

hence, in this simplified setting, it appears to be the greenhouse effect, the capability to radiate out the heat in the higher atmosphere, that keeps convection going.
billiards
#14
Aug28-08, 03:53 PM
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Why is cooling by radiation more important at higher altitudes? I can see how the inverse would be true: that heating by absorption would be more important as a mechanism of heat transfer at higher altitudes, simply because there is no surface to conduct heat to the air at high altitudes. I guess what we really need to know is the net effect, in terms of relative importance, as to the effect of greenhouse gases to heat transfer as a function of altitude. If it turns out that air at high altitude emits radiation at a higher rate than it absorbs then this is unstable and convection may ensue.

Of course, we have convection, and we can explain it without the need to resort to this effect. Then we may reasonably ask, how important is this effect? What is the relative order of magnitude of this effect in relation to the standard model of atmospheric convection: hot air rises, expands and cools, advects, and sinks. Afterall, the concept of the Hadley cell, which fits global observations of convection patterns neatly, does not rely on this effect. This might suggest that this effect, if it exists at all, is negligible.
Andre
#15
Aug29-08, 12:58 AM
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See the OP. Jack:

According to our estimates, convection accounts for 67%, water vapor condensation in troposphere accounts for 25%, and radiation accounts for about 8% of the total heat transfer from the Earth’s surface to troposphere.
Andre
#16
Aug29-08, 05:18 AM
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Another way of looking at it is measuring the temperature/altitude of the outgoing radiation emitted by CO2 and H2O

http://www.bom.gov.au/weather/satell...atpix.shtml#wV

In normally moist atmosphere , most of the WV radiation recieved by the satellite originates in the 300-600 hPa layer, but when the air is dry some radiation may come from layers as low as 800hPa.
So if these are the normal atmospheric levels that radiate IR energy out, as a consequence, these levels should logically be cooling.
billiards
#17
Aug31-08, 02:57 PM
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Quote Quote by Andre View Post
See the OP. Jack:
Andre, the quote is meaningless in terms of my objections. I'm not objecting to the assertion that convection is important, and that if there were more convection we would lose heat quicker and thus cool, I agree with that point. I was objecting to whether the presence of CO2 actually had a sensible impact on atmospheric convection.


Quote Quote by Andre View Post
Another way of looking at it is measuring the temperature/altitude of the outgoing radiation emitted by CO2 and H2O

http://www.bom.gov.au/weather/satell...atpix.shtml#wV



So if these are the normal atmospheric levels that radiate IR energy out, as a consequence, these levels should logically be cooling.
I'm sorry, you're going to have to spell this one out to me. I really don't follow your point.
Gokul43201
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Aug31-08, 04:28 PM
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Also, in this context, perhaps someone might like to comment on the following paper.

Lunt et al, Nature 454, 1102-1105 (2008)
Quote Quote by Nature
Late Pliocene Greenland glaciation controlled by a decline in atmospheric CO2 levels

Abstract: It is thought that the Northern Hemisphere experienced only ephemeral glaciations from the Late Eocene to the Early Pliocene epochs (about 38 to 4 million years ago), and that the onset of extensive glaciations did not occur until about 3 million years ago. Several hypotheses have been proposed to explain this increase in Northern Hemisphere glaciation during the Late Pliocene. Here we use a fully coupled atmosphereľocean general circulation model and an ice-sheet model to assess the impact of the proposed driving mechanisms for glaciation and the influence of orbital variations on the development of the Greenland ice sheet in particular. We find that Greenland glaciation is mainly controlled by a decrease in atmospheric carbon dioxide during the Late Pliocene. By contrast, our model results suggest that climatic shifts associated with the tectonically driven closure of the Panama seaway, with the termination of a permanent El Ni˝o state or with tectonic uplift are not large enough to contribute significantly to the growth of the Greenland ice sheet; moreover, we find that none of these processes acted as a priming mechanism for glacial inception triggered by variations in the Earth's orbit.
http://www.nature.com/nature/journal...ture07223.html


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